Oldman 2 Wind Farm Limited

Transcription

1 Decision D Spring 2017 Comprehensive Sound Survey at Receptors R and S August 25, 2017

2 Alberta Utilities Commission Decision D Proceeding Application A001 August 25, 2017 Published by the: Alberta Utilities Commission Fifth Avenue Place, Fourth Floor, 425 First Street S.W. Calgary, Alberta T2P 3L8 Telephone: Fax: Website:

3 Contents 1 Decision summary Introduction and background Comprehensive noise survey Equipment and representative conditions Isolation analysis Comments from residents Three hours of cumulative data and low frequency noise Results Commission findings Validity of comprehensive noise survey Compliance with daytime and nighttime permissible sound levels Decision... 9 Decision D (August 25, 2017) i

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5 Alberta Utilities Commission Calgary, Alberta Decision D Spring 2017 Comprehensive Sound Survey Proceeding at Receptors R and S Application A001 1 Decision summary 1. In this decision, the Alberta Utilities Commission must decide whether the Oldman 2 Wind Farm submitted by at the direction of the Commission demonstrates compliance with permissible sound levels set out in Rule 012: Noise Control. 2. For the reasons set out below, the Commission finds that the sound survey submitted by demonstrates that the Oldman 2 Wind Farm is not in compliance with the established nighttime permissible sound level of 40 decibels A-weighted (dba Leq), but is in compliance with the established daytime permissible sound levels of 50 dba Leq. acknowledged its non-compliance with the nighttime permissible sound level and has implemented a temporary solution to address it. 3. Accordingly, the Commission directs to conduct a comprehensive sound survey at receptors R (Yanke) and S (Huebner) to demonstrate compliance with the nighttime permissible sound level and submit its report by December 1, Introduction and background 4. In Decision 3521-D , 1 the Commission found that the Oldman 2 Wind Farm was not in compliance with Rule 012 because it did not meet the permissible sound level of 40 dba Leq nighttime at the Yanke and Huebner residences. The Commission ordered (Oldman 2) to immediately restrict operations of the wind turbines of the Oldman 2 Wind Farm contributing to the non-compliance with the permissible sound levels at these residences and conduct a follow-up study. 5. On August 5, 2015, Oldman 2 confirmed that it had restricted operations at the Oldman 2 Wind Farm by implementing a reduced noise operation mode on wind turbines T19 and T20 to achieve compliance with the permissible sound levels determined in Decision 3521-D In the reduced noise operation mode these wind turbines were running at a reduced rotational speed and reduced power output level to reduce noise emission levels and each turbine was six dba lower than the normal operating mode. Oldman 2 stated that it had yet to complete the modelling exercise to optimize the new operation mode and to provide confirmation of the exact new noise levels at the Yanke and Huebner residences. Subsequently, on August 12, 2015, Oldman 2 stated that only the nearest wind turbine (T20) was being operated in a reduced mode that is five dba lower than the normal mode. Wind turbine T19 had been returned to normal mode. It added that the noise levels from the Oldman 2 Wind Farm at 1 Decision 3521-D : Mr. Yanke and Mr. Huebner Noise Complaints, Oldman 2 Wind Farm, Proceeding 3521, Application , July 20, Decision D (August 25, 2017) 1

6 the Yanke and Huebner residences were predicted to be 39.6 dba Leq and 38.4 dba Leq, respectively On September 18, 2015, Oldman 2 filed a review application of Decision 3521-D with the Alberta Utilities Commission. The Commission denied the review application in Decision D and directed Oldman 2 and the operator, Mainstream Renewable Power Limited, to conduct a comprehensive sound level survey in accordance with its letter of June 15, 2016 and file the comprehensive sound level survey report in Proceeding 3521 because noise levels from the Oldman Wind Farm had not been measured at the Yanke and Huebner residences to determine compliance with the established nighttime permissible sound levels. 7. In response to the above-noted direction, Oldman 2 submitted the Oldman 2 Wind Farm (comprehensive noise survey) on May 31, The comprehensive noise survey, conducted by SLR Consulting (Canada) Ltd. (SLR), was registered as Proceeding On May 31, 2017, Oldman 2 also filed an in which it stated that the Oldman 2 Wind Farm was not compliant with the nighttime permissible sound level at the Yanke and Huebner residences and that, as a result, it had implemented steps to reduce the wind noise pending further investigations A notice of application was issued on June 13, 2017, 5 and a statement of intent to participate in the proceeding was registered on June 27, 2017 by Mr. Jesse Yanke On July 4, 2017, the Commission received a request from Mr. Yanke for a one month time extension to file submissions. The Commission granted Mr. Yanke until August 8, 2017 to file submissions The Commission issued information requests to Oldman 2 on July 4, 2017 and responses were received on July 14, Mr. Yanke did not file any further submissions by the August 8, 2017 deadline. 13. The Commission considers August 8, 2017 to be the close of record for Proceeding Comprehensive noise survey 14. SLR conducted the comprehensive sound survey over 27 daytime and nighttime periods between April 13, 2017 and May 10, 2017 at two receptor locations 8 identified as R and S. 9 2 Proceeding 3521, Oldman 2 AUC Submittal Letter Decision D : Review of Decision 3521-D , Proceeding 20843, Application A001, June 15, Exhibit X0014, describing initial non-compliance. 5 Exhibit X0013, Notice Exhibit X0017, System generated PDF. 7 Exhibit X0023, AUC Ruling on time extension request to file submissions. 2 Decision D (August 25, 2017)

7 15. The permissible sound levels at the two receptor locations were previously established at 50 dba Leq daytime and 40 dba Leq nighttime in Decision 3521-D Receptor R was described as being located on the side of the river valley with the valley bank rising to the north. The nearest wind turbine (T20) is located approximately 300 metres to the north-northwest of the dwelling. Receptor S was described as being located near the bottom of the river valley. The nearest wind turbine (T20) is approximately 475 metres to the north-northwest of the dwelling. SLR stated that the Oldman 2 wind turbines at these dwellings were typically audible when the ground level winds were moderate but that the turbines were producing over 78 per cent of their maximum power. This occurred frequently during the sound survey Equipment and representative conditions 17. SLR set up Type 1 sound level meters fitted with primary windscreens and secondary windscreens and portable weather stations at each of the two receptor locations in accordance with Rule 012. The microphones were located 15 metres north of the dwellings in the direction of the nearest wind turbine (T20) and were field calibrated at the start and end of the sound surveys in accordance with the rule. 18. SLR stated that in order to meet environmental protection criteria, the Oldman 2 wind turbines were set to a minimum hub height cut-in wind speed of 5.5 metres per second (m/s) during the time period from 30 minutes before dusk until 30 minutes after dawn. In addition, wind turbine T20 was operated in reduced sound power mode which limited the maximum turbine electrical power to 1,824 kilowatts (kw) during the survey for all nighttime periods SLR noted that the wind directions corresponding to the prevailing wind direction in the study area did not indicate that representative conditions included downwind conditions at the receptor locations. 12 Oldman 2 conducted an analysis of historical wind data collected at the pre-construction mast 901 between February 2003 and February 2013 and found that receptors R and S would have been downwind of the nearest wind turbine (T20), only 1.0 per cent and 1.1 per cent of the time, respectively. Due to this very low rate of occurrence, downwind conditions were not considered by Oldman 2 to be representative of the prevailing wind conditions at receptors R and S. 13 In addition, comments from the resident at Receptor R indicated that the noise is most noticeable under winds from the west-southwest and the resident at Receptor S indicated the noise is most noticeable under west winds. 3.2 Isolation analysis 20. SLR isolated the noise data using a combination of automated and manual identification methods with the intent to determine whether wind turbine noise exceeded the permissible levels at the receptor locations. All isolation methods were verified by listening to many instances of each type of isolated event to ensure the identification algorithms were working correctly and were not isolating representative data. SLR conducted isolation analyses of sound level data 8 Exhibit X0003, Report, PDF page Exhibit X0003, Report, PDF page Exhibit X0003, Report, PDF page Exhibit X0003, Report, PDF page 12 and Exhibit X0003, Report, PDF page 16 and Exhibit X0003, Report, PDF page 16. Decision D (August 25, 2017) 3

8 collected based on wind turbine power output, wind speed and direction, wind noise, abnormal noise events, precipitation, snow cover as outlined in Rule SLR removed data when the closest wind turbine (T20) was operating at less than 78 per cent of its rated capacity. SLR made the assumption that the maximum noise emissions were generated by the nearest wind turbine when it operated at a reduced electrical power output of 1,825 kw during the nighttime period. 22. Measured data was removed for durations where the receptor was not downwind (± 45 ) of the nearest wind turbine. SLR stated that wind direction was based on the heading of the wind turbine nacelle, rather than wind direction at the receptor locations since wind direction is often affected by structures and terrain in the immediate vicinity, and is not representative of the average wind direction in the area. SLR stated that downwind conditions were not cited by receptors R and S as being representative of the noise complaints. 23. SLR removed wind-induced noise generated by wind passing over the microphone windscreen, and blowing over obstacles, structures, trees, and shrubs. SLR stated that [f]or these particular receptor locations during this survey period, SLR determined that wind noise contributions corresponding to a 6 m/s maximum wind speed did not significantly affect measured sound levels around 40 dba. Likewise, for these particular receptor locations during this survey period, SLR determined that wind noise contributions corresponding to an 8 m/s maximum wind speed did not significantly affect measured sound levels around 50 dba. 14 SLR isolated wind-induced noise by removing data where the wind speed exceeded six m/s during the nighttime periods and eight m/s during the daytime periods. 24. Abnormal noise events such as distant trains and train whistles, dogs barking, birds and farm machinery were identified and isolated by listening to the audio recordings. SLR stated that wind turbines are not expected to have short-duration sound level spikes that approach 70 dba at the receptor locations and it removed these data from the measured data set. 3.3 Comments from residents 25. SLR stated that residents at receptors R and S provided comments with respect to the sound levels from the Oldman 2 Wind Farm and were provided Appendix 4 - Noise complaint investigation forms from Rule In the Appendix 4 - Noise complaint investigation forms event log, Mr. Yanke at Receptor R indicated that wind turbine noise is audible at both indoor and outdoor locations and described it as steady whooshing, pulsing whooshing and high pitch gearbox noise. In response to information request OM2-AUC-2017JUL04-012, SLR expanded on the comments in the event log stating that wind turbine noise was clearly audible during wind speeds ranging from 10 kilometres per hour to 75 kilometres per hour, and blade turbulence noise and gearbox noise sources were both audible. Oldman 2 stated that through listening to audio recordings, wind turbine noise is largely masked by wind-induced noise for wind speeds approaching 20 m/s Exhibit X0025, AUC IR Round 1 - Receptors R S - SLR Response (E) OM2-AUC-2017JUL (b). 15 Exhibit X0025, AUC IR Round 1 - Receptors R S - SLR Response (E OM2-AUC-2017JUL (a). 4 Decision D (August 25, 2017)

9 3.4 Three hours of cumulative data and low frequency noise 27. SLR also referenced comments and noise complaint investigation forms submitted in response to the AUC Information Requests Round 1 submitted in Proceeding 3521, Application In those forms Mr. Yanke at Receptor R indicated that the noise is most noticeable under west southwest winds, and Mr. Huebner at Receptor S indicated the noise is most noticeable under west winds. SLR noted that these comments indicate that the wind turbine noise is most noticeable under the prevailing wind directions SLR acknowledged that Rule 012 requires that a minimum of three cumulative hours of valid data be obtained in a daytime or nighttime period for the daytime or nighttime energy-average sound pressure level (Leq) value for that period to be considered valid, and that if multiple daytime or nighttime periods are deemed valid, the highest daytime and nighttime Leq values are to be used to assess compliance. 17 SLR explained that a major constraint in obtaining valid downwind data is the limited durations where the wind speed at hub-height was sufficient to produce maximum sound power levels but the wind speed at the microphone height is low enough such that the wind noise on the microphone does not excessively influence the measured sound level. Although SLR utilized secondary windscreens to minimize the wind noise as much as practical, wind noise remained the primary reason for the isolation of data while the wind turbines were producing maximum sound power At Receptor R, 0.5 hours of cumulative valid data was obtained during the daytime periods after isolating for downwind conditions and no valid data was obtained under downwind conditions during the nighttime periods. At Receptor S, 0.7 hours and 0.2 hours of cumulative valid data was obtained during the daytime and nighttime periods respectively after isolating for downwind conditions. 19, 20 Consequently, based on historical wind data and comments from the residents, SLR stated that representative conditions were determined to not include downwind sound propagation. 21 Subsequently, the results without isolation analysis for downwind conditions showed that 3.9 hours of valid data were collected for the daytime period at Receptor R during one daytime period, however, less than three hours of valid data were recorded for the daytime periods for Receptor S and for the nighttime periods at receptors R and S. The valid data collected over the duration of the survey was then combined to form the daytime and nighttime data sets for the daytime periods at Receptor S and for the nighttime periods at receptors R and S that were compared to the daytime and nighttime permissible sound levels in determining compliance with Rule 012. SLR conducted an evaluation of low frequency noise (LFN) at each of the two receptor locations in accordance with Rule 012 although LFN was not identified as a potential problem at the Oldman 2 Wind Farm. 22 Oldman 2 stated that it was not aware of any complaints registered with respect to low frequency noise associated with the existing complaints Exhibit X0003, Report, PDF page Exhibit X0003, Report, PDF page Exhibit X0003, Report, PDF page Exhibit X0003, Report, PDF page Exhibit X0025, AUC IR Round 1 - Receptors R S - SLR Response (E OM2-AUC-2017JUL04-010), PDF pages 18 to Exhibit X0003, Report, PDF page Exhibit X0003, Report, PDF page Exhibit X0025, AUC IR Round 1 - Receptors R S - SLR Response (E) OM2-AUC-2017JUL (a). Decision D (August 25, 2017) 5

10 30. SLR collected third octave data in the event that a check for a tonal component was required. SLR determined that although the difference between the C-weighted and the A-weighted isolated sound levels exceeded 20 db in a number of instances, the third octave band analysis did not identify the presence of any audible tone. In addition, the wind turbine manufacturer indicates that these wind turbines produce no tonal audibility above three db. SLR concluded that a LFN condition does not exist because the wind turbines do not generate a tonal component between 20 and 250 Hz Results 31. SLR stated that three hours of cumulative valid daytime data were collected at Receptor R; however, three hours of cumulative valid data were not obtained in any single daytime period at Receptor S. Additionally, three hours of cumulative valid data were not obtained in any single nighttime period at both receptor locations. 32. In instances where three hours of valid data were not obtained in a single daytime or nighttime period, SLR assessed compliance by comparing the Leq of all of valid daytime or nighttime data collected over the duration of the study without isolation for downwind conditions, to their respective permissible sound levels. 33. Data results were presented for the daytime and nighttime periods with and without downwind direction isolation analysis criteria implemented. 25 Data provided without downwind direction isolation analysis criteria allowed for an increase in the amount of valid hours analyzed. SLR stated that the intent of the comprehensive sound survey was to evaluate compliance of the wind turbine noise with respect to the permissible sound levels. As such, the reported isolated values may include contributions from extraneous noise events or wind noise that did not require isolation to show compliance with the permissible levels. 26 In SLR s opinion, the isolated comprehensive sound levels are appropriate for comparison to the permissible sound levels set out in Rule 012 because they are typical of the prevailing wind directions in the study area and are representative of conditions typically experienced at receptors R and S SLR concluded that the comprehensive noise survey results show that the isolated daytime sound levels are lower than the daytime permissible sound level but the isolated nighttime sound levels are higher than the nighttime permissible sound level. This result indicates that the Oldman 2 Wind Farm was in compliance with Rule 012 during the daytime, but not in compliance during the nighttime. 35. Furthermore, Oldman 2 stated in an to the Commission that the results of the comprehensive survey concluded that the Oldman 2 Wind Farm was non-compliant with the nighttime permissible sound level. In response to these results, Oldman 2 implemented a strategy to reduce nighttime noise emissions by shutting off wind turbine T20 during the nighttime periods and running wind turbine T19 in the minus three db mode during the nighttime periods Exhibit X0003, Report, PDF page Exhibit X0012, AUC IR Round 1 - Receptors B J K - SLR Response (E) 3.0 OM2-AUC-2017JUN22-003, PDF page 18 to Exhibit X0003, Report, PDF page Exhibit X0003, Report, PDF page Exhibit X0014, describing initial non compliance. 6 Decision D (August 25, 2017)

11 These temporary solutions to reducing noise levels were confirmed in Oldman 2 s response to OM2-AUC-2017JUL (a) With the current mitigation measures, Oldman 2 stated that the expected total nighttime Oldman 2 Wind Farm noise contribution at Receptor R and Receptor S is expected to be 35.9 dba Leq and 36.1 dba Leq. 30 Oldman 2 added that the current mitigation strategy is very conservative, and has been implemented as a short-term strategy to ensure compliance at receptors R and S. Oldman 2 is presently working together with both Siemens, the turbine manufacturer, and SLR to identify permanent mitigation measures to achieve compliance at receptors R and S. The current mitigation measures will remain in place until a permanent mitigation strategy is identified. 31 Oldman 2 stated that it intends to conduct a new comprehensive sound level survey following identification and implementation of a permanent mitigation strategy. 4 Commission findings 37. In making its decision on this application, the Commission must consider whether the comprehensive noise survey at receptors R and S was conducted in accordance with Rule 012 and determine whether the nighttime and daytime permissible sound levels at receptors R and S are in compliance with Rule Validity of comprehensive noise survey 38. The Commission accepts that when the comprehensive noise survey was conducted, the sound equipment and portable weather stations were set up and calibrated to meet the requirements in Rule The Commission considers that the isolation analysis performed on the representative daytime and nighttime data using audio recordings and observations to be reasonable. It also accepts that the nearest wind turbine (T20) was operated in reduced sound power mode which limited the maximum turbine electrical power to 1,824 kw during the survey for all nighttime periods. 40. The Commission acknowledges that obtaining three hours of valid cumulative downwind data was a challenge during the three-week noise survey and notes the review of historical annual wind data collected at the pre-construction mast 901 between February 2003 and February 2013 indicates that the dwellings at receptors R and S are not located typically in a downwind direction with respect to the predominant wind direction. The historical data showed that receptors R and S would have been downwind of the nearest wind turbine (T20) with hub-height wind speeds between 9.7 m/s and cut-out (25 m/s) 1.00 per cent and 1.1 per cent of the time, respectively. Without using the isolation analysis filter for downwind conditions, the amount of daytime data collected at Receptor R increased from 0.5 hours to a total of 26.8 hours and the daytime hours at Receptor S increased from 0.7 hours to 17.5 hours. For the nighttime 29 Exhibit X0025, AUC IR Round 1 - Receptors R S - SLR Response (E), OM2-AUC-2017JUL (a). 30 Exhibit X0025, AUC IR Round 1 - Receptors R S - SLR Response (E), OM2-AUC-2017JUL (b) and (c). 31 Exhibit X0025, AUC IR Round 1 - Receptors R S - SLR Response (E), OM2-AUC-2017JUL (c) and (d). Decision D (August 25, 2017) 7

12 periods, there was still insufficient valid data collected at receptors R and S. Without using the isolation analysis filter for downwind conditions and by adding the valid data over the entire survey period for each daytime and nighttime period, the amount of nighttime data collected at receptors R and S increased from having no data collected to a total of 6.3 hours and 4.6 hours, respectively. In light of the low rate of occurrence of downwind conditions from the nearest wind turbine for receptors R and S in this survey, the Commission exempts Oldman 2 from the collection of valid downwind data at receptors R and S for this study. It considers that in these circumstances it was reasonable to use the average of the cumulative valid daytime and nighttime measurements over the three-week comprehensive noise survey for the evaluation of compliance with the permissible sound level. 41. Furthermore, noting that wind turbines are not likely to produce short-duration sound level spikes approaching 70 dba at the receptor locations, the Commission finds that based on field observations and the review of the audio recordings, it was reasonable to use automated isolation of abnormal noise events at receptors R and S. 42. The Commission is satisfied that the potential for a low frequency noise condition does not exist with the wind turbines which comprise the Oldman 2Wind Farm because third octave band analysis did not identify the presence of any audible tone, and the turbine manufacturer states that these wind turbines produce no tonal audibility above three db. 43. Based on the above findings, the Commission accepts that the comprehensive noise survey at receptors R and S was conducted in keeping with Rule Decision D (August 25, 2017)

13 4.2 Compliance with daytime and nighttime permissible sound levels 44. In the following tables prepared by SLR, the isolated sound levels determined in the comprehensive noise survey are summarized and compared to the permissible sound levels set out in Rule 012. Table G: Comparison of Isolated Sound Levels to AUC Daytime Permissible Sound Levels Receptor ID Date of Daytime Period Hours of Valid Data in Daytime Period Isolated Daytime Comprehensive Sound Level (dba Leq) AUC Daytime Permissible Sound Level (dba Leq) Margin of Compliance (dba Leq) R April 17-18, S All Periods Note 1: Calculated as the energy-average of all valid daytime data Table H: Comparison of Isolated Sound Levels to AUC Nighttime Permissible Sound Levels Receptor ID Date of Nighttime Period Hours of Valid Data in Nighttime Period Isolated Nighttime Comprehensive Sound Level (dba Leq) AUC Nighttime Permissible Sound Level (dba Leq) Margin of Compliance (dba Leq) R All Periods S All Periods Note 1: Calculated as the energy-average of all valid nighttime data 45. Given the above-noted results and these particular circumstances, the Commission finds that the Oldman 2 Wind Farm complies with the established daytime permissible sound level of 50 dba Leq. The Commission further finds that the Oldman 2 Wind Farm is not in compliance with the established nighttime permissible sound level of 40 dba Leq at the two receptor locations. 5 Decision 46. The Commission is satisfied that the comprehensive noise survey conducted at receptors R (Yanke) and S (Huebner) demonstrates compliance with the daytime permissible sound levels as prescribed in Rule 012. The Commission further finds that the Oldman 2 Wind Farm has not demonstrated compliance with the established nighttime permissible sound level of 40 dba Leq at the two receptor locations. 47. The Commission acknowledges that Oldman 2 has implemented a short-term strategy to reduce nighttime noise emissions by shutting off wind turbine T20 during the nighttime periods and running wind turbine T19 in the minus three db mode during the nighttime periods, and has committed to continuing this short-term strategy until permanent mitigation measures to achieve compliance at receptors R and S are identified. Oldman 2 has also committed to conducting a new comprehensive sound survey following identification and implementation of a permanent Decision D (August 25, 2017) 9

14 mitigation strategy. Given that compliance with the established nighttime permissible sound level is at issue, the Commission directs Oldman 2: a. To continue with the above-noted mitigation measures and any others it may identify to reduce nighttime noise emissions at receptors R and S, until it can demonstrate compliance with the established nighttime permissible sound levels. b. To conduct a comprehensive sound survey at both receptors R and S to demonstrate compliance with the nighttime permissible sound level and submit its report to the Commission by December 1, c. In conducting the comprehensive sound survey, measurements must be taken with wind turbine T19 in the minus three db mode and wind turbine T20 turned off. Additional measurements may be taken for the comprehensive sound level survey using any alternate noise control method or mitigation to achieve compliance with Rule 012. Dated on August 25, Alberta Utilities Commission (original signed by) Anne Michaud Commission Member 10 Decision D (August 25, 2017)